Comparative assessment of greenhouse gas emissions from cattle manure storage and management systems in the haor wetlands ecosystem of Bangladesh

The global livestock sector is a major contributor to greenhouse gas (GHG) emissions, with manure management being a critical source of methane (CH₄), nitrous oxide (N₂O), and carbon dioxide (CO₂). This study conducted a comparative assessment of GHG emissions from cattle manure under pit and heap storage methods in three representative locations within Bangladesh's ecologically sensitive wetland ecosystem: Mitamoin, Itna, and Austagram. Using the closed chamber technique and gas chromatography, gas fluxes were monitored alongside environmental parameters. Results revealed that pit storage consistently produced significantly higher emissions across all measured gases compared to heap storage. Specifically, CH₄ emissions from pit storage (409.89 ± 27.54 mg m⁻² d⁻¹) were approximately 2.4 times higher than from heap storage (167.56 ± 25.88 mg m⁻² d⁻¹), while N₂O (3.14 ± 0.80 mg m⁻² d⁻¹ vs. 1.53 ± 0.83 mg m⁻² d⁻¹) and CO₂ (4489.33 ± 566.38 mg m⁻² d⁻¹ vs. 1790.67 ± 347.92 mg m⁻² d⁻¹) emissions were also markedly elevated. Regression and correlation analyses identified the storage method as the primary driver of emission dynamics, with temperature and pH as secondary regulators. While CO₂ dominated the total emission profile, CH₄ contributed a substantial secondary share, particularly in pit systems. Furthermore, Austagram exhibited the highest overall emissions, indicating significant site-specific variability. These findings underscore that traditional pit storage is large source of GHGs. The study highlights the urgent need for climate-smart manure management strategies, such as improved aeration or location-specific heap management, to mitigate the environmental footprint of livestock production in Bangladesh's haor ecosystems.